The present invention is related to a speed control device of a treadmill. The speed control device includes an ultrasonic transmitter and an ultrasonic receiver arranged on a controlling panel of the treadmill. The ultrasonic wave transmitted by the transmitter can be truly reflected and received by the receiver so as to accurately calculate the distance of the user and control the speed of the treadmill.
Referring to FIG. 7, a conventional treadmill includes a base seat 4 and a tread platform 5. The base seat 4 has two upward extending columns 4. A panel 42 is mounted between the top ends of the columns 41 for controlling and adjusting the speed and slope of the treadmill. A front section of the tread platform 5 is mounted between the two columns 41. A tread belt 51 is circularly rotatably disposed in the tread platform 5. The panel 42 is spaced from a user by a certain distance. In treading, when the user desires to operate the treadmill, for example, slow down the speed, the user must tilt his/her body forward to get close to the panel 42 so as to operate the panel 42 for slowing down the speed. When changing the treading attitude, the original coordinated treading movement of the user will be interrupted.
Moreover, when operating the panel 42, the user must see the panel 42 to select a desired press key. However, the user is in a dynamic state, while the panel 42 is in a static state. Furthermore, the user is in a passive state. Therefore, it is hard to the user to aim at the press key of the panel 42. As a result, the user may mispress a press key. Especially when the user can hardly bear the exercise and want to stop the treadmill, the user will be unable to accurately press a correct press key of the panel 42 to stop the treadmill in time. Under such circumstance, the user may fall down. This is extremely dangerous.
In order to avoid the above situation, the treadmill is equipped with a safety device having a security rope 6. One end of the security rope 6 is fixed on the panel 42 and connected with the internal circuit. The other end of the rope 6 has a clip 61 clipping a user""s body. The security rope 6 has a certain length. In case the use backs up due to insufficient strength, the security rope 6 is pulled backward to detach from the panel 42. At this time, the treadmill is powered off and stopped so as to ensure safety in use.
However the security rope 6 is connected to the user""s body. Accordingly, the security rope 6 will more or less interfere with the movement of the user. In addition, in case the user forgets to use the safety device, the safety of the user cannot be ensured. Furthermore, the safety device can only stop the treadmill, while failing to control the speed thereof.
FIG. 8 shows another type of treadmill having an ultrasonic detection device. A tread platform 72 having a tread belt 71 is mounted on a bed 7. A driving device 73 is disposed at one end of the bed 7 for driving the tread belt 71. Two support columns 74 are disposed on two sides of the bed 7 and adjacent to the driving device 73. A transverse beam 75 is fixed between inner sides of the support columns 74 in a position higher than the tread belt 71. A controlling unit 8 is disposed in the middle section of the transverse beam 75. The transverse beam 75 is formed with an opening 751 facing the tread belt 71. The controlling, unit 8 includes a transmitter section, a receiver section and a timer section. The transmitter section has a pulse generator and a transmitter. The pulse generator serves to oscillate the ultrasonic wave to generate high frequency sonic speed. The transmitter transmits the ultrasonic wave to the user to detect the position of the user. The receiver section has a receiver for receiving the ultrasonic pulse reflected from the user. The timer section calculates the going and returning time of the ultrasonic wave. On the basis of the ultrasonic speed, the going and returning distance of the ultrasonic wave is calculated and sent to the controlling panel of the treadmill so as to control the speed of the tread belt. In case the user fails to bear the exercise and backs out of a set distance, the treadmill is stopped to prevent the user from falling down.
However, the controlling unit 8 of the treadmill is mounted inside the transverse beam 75. The transverse beam 75 must be first welded on the treadmill and then the transverse beam 75 is formed with the opening 751 for mounting the controlling unit 8. Then it is necessary to layout the wires to connect the controlling unit 8 with the CPU in the panel 76. Such procedures are quite complicated.
Furthermore, the controlling unit 8 of the treadmill is mounted inside the transverse beam 75 and the ultrasonic wave is transmitted to the legs of the user. When treading, the user""s legs continuously alternately move. This will affect the reflection of the ultrasonic wave. Especially after reflected, the ultrasonic wave will be weakened so that the received signal will be weaker and disordered. As a result, it is hard to truly measure the distance of the user and the speed of the treadmill may be maladjusted.
Besides, the controlling, unit 8 of the treadmill is mounted inside the transverse beam 75 and positioned in a too low position. In the case a kid plays on the treadmill, the controlling Unit 8 will sense the kid to rotate the tread belt 71 of the treadmill. This will frighten the kid and even make the kid fall down.
In addition, the transverse beam 75 is positioned above the tread belt 71. When a user treads on the tread belt 71, the user""s legs may incautiously hit the transverse beam 75 and get hurt. Moreover, when folding the treadmill, the transverse beam 75 will interfere with the folding of the tread platform 72 as shown in FIG. 9. As a result, the rear end of the tread platform 72 can be hardly folded to firmly lean on the bed 7.
Therefore, it is necessary to provide a measure for more accurately detecting the distance of a user and simplifying the manufacturing procedure of the treadmill without interfering with the operation thereof.
It is therefore a primary object of the present invention to provide a speed control device of a treadmill. The speed control device is arranged in a certain position on a controlling panel of the treadmill. The speed control device includes a transmitter, a receiver, a transmitter end circuit and a receiver end circuit. The transmitter and the receiver are mounted on the control ling panel of the treadmill and directed to rear end of the treadmill. The transmitter serves to generate and transmit ultrasonic wave, while the receiver serves to receive reflected ultrasonic wave. The transmitter end circuit is disposed in the controlling panel and connected with a CPU and the transmitter inside the controlling panel. The transmitter end circuit has an oscillating IC circuit and an analog-digital converting circuit. The oscillating IC circuit serves to oscillate the ultrasonic wave generated by the transmitter to high frequency. The analog-digital converting circuit serves to convert the digital signal of the CPU into analog signal, The receiver end circuit is disposed in the controlling panel and connected with the CPU and the receiver inside the controlling panel. The receiver end circuit has an amplifying circuit and an analog-digital converting circuit. The amplifying circuit serves to amplify the reflected ultrasonic wave received by the receiver into high frequency. The analog-digital converting circuit serves to convert the reflected analog signal into digital signal and send the signal to the CPU. The transmitter and the receiver of the controlling device are arranged on the controlling panel of the treadmill that is positioned at a height substantially equal to the height of upper half of a user""s body. Therefore, the transmitted ultrasonic wave is reflected by the upper half of the user""s body to be received by the receiver. Accordingly, the distance of the user can be accurately detected by way of ultrasonic wave and thus the CPU of the controlling panel can truly control the speed of the treadmill.
It is a further object of the present invention to provide the above speed control device in which the transmitter and the receiver are pivotally connected with a seat body. Therefore, the transmission and receiving angles of the transmitter and the receiver can be adjusted in accordance with different heights of users. Therefore, the transmitter and the receiver can truly detect the user. In addition, the transmitter and the receiver have a certain pivot angle range so that the transmission and receiving of the transmitter and the receiver are limited to a certain height. Accordingly, a kid will not misactivate the treadmill.
It is still a further object of the present invention to provide the above speed control device in which the controlling device is arranged on the controlling panel of the treadmill without procedures of welding, perforation and layout of wire. Therefore, the manufacturing and processing time and labor are reduced. Also, the controlling device is mounted in such a position as not to interfere with the treading movement of the user and the folding operation of the tread platform.